Asian soybean rust (ASR), caused by Phakopsora pachyrhizi (Syd.), poses a serious threat to global soybean production. The main approach to managing this disease has been through repeated fungicide applications which have reduced efficacy due to fungicide resistance. Recently, spray-induced gene silencing (SIGS) through exogenous application of double-stranded RNA (dsRNA) has emerged as a promising approach for plant disease management. In the present study, twelve different dsRNAs targeting genes important for P. pachyrhizi urediniospore germination, infection of the host plant or resistant to commonly used fungicides were produced in Escherichia coli on a large scale. Nine of these dsRNAs significantly reduced ASR severity (by 24.0% to 81.1%) and fungal biomass (50.5% to 83.1%) compared to the control when applied as a foliar spray in our growth chamber studies. Three of the most effective dsRNAs targeting an acyltransferase (ACE), cytochrome B (CYTB1) and a reductase (S12) also significantly reduced disease severity (78.2 to 82.3%) and fungal growth (79.8 to 85.4%) compared to the control in the greenhouse studies. Further investigation of the P. pachryrhizi urediniospore germination and hyphal growth in the presence of these dsRNAs in vitro revealed these dsRNAs reduced the spore germination rate from 72.1% to 0.0–26.6% at 4.5 h and hyphal growth from 254.0 µm to 2.7–40.5 µm at 9 h, with dsRNA targeting the S12 gene being the most effective. These results highlight the potential of SIGS using selected dsRNAs as a sustainable strategy for managing ASR through suppressing urediniospore germination and hyphal growth.

The research was conducted at Kaski, Nepal from March to June 2021 to study different doses of vermicompost and inorganic fertilizers on growth and yield of radish (Raphanus sativus) The experiment was laid out in a two-factor Randomized Complete Block Design (RCBD) with 12 treatments and 3 replications. The first factor was variety—Tokinashi and Mino Early—and the second factor was fertilizer level, consisting of six treatments: control (no fertilizer), 75% vermicompost + 25% inorganic fertilizer, 50% vermicompost + 50% inorganic fertilizer, 25% vermicompost + 75% inorganic fertilizer, 100% inorganic fertilizer, and 100% vermicompost. Vegetative parameters were recorded at 20, 30, 40 and 50 days after sowing whereas yield parameters: biological yield per plant, economic yield per plant, root length and root diameter were recorded at 55 days after sowing. It has been observed that the growth and yield attributing characters of radish were significantly affected by variety and fertilizer levels. Mino early recorded highest result for all vegetative parameters. However, highest yield attributing characters was recorded from Tokinashi. The combination of inorganic fertilizer with 50-75% with vermicompost gave better result in terms of both growth and yield attributing parameters than 100% inorganic fertilizer alone. Interaction effect of variety and fertilizer levels for all parameters at all dates of observations was found to be non-significant. Overall, the highest yielded was from variety, Tokinashi (4.55kg/m2) and the fertilizer combination of 50% vermicompost + 50% inorganic fertilizer (5.61kg/m2). Therefore, this combination is recommended for late-season radish production in Kaski, Nepal. Int. J. Appl. Sci. Biotechnol. Vol 13(4): 153-161.